Thoughts on Obligation

[Michiharu Kudoh <KUDO@jp.ibm.com>]

Hi, Bill

I have several comments and questions
on your Wiki example.
http://wiki.oasis-open.org/xacml/ScratchPad

1) In your obligation example, you use
"kind" and "category" attribute to describe the categories
of the obligation. I am wondering if this attribute should be separate
attribute or be a part of the obligation ID. If there exists an obligation
that belongs to two or more categories, then the idea to have a separate
attribute would make sense. However, if most of the obligation belongs
to only one category, then having separate attribute is questionable. To
validate this idea, please give me an obligation example that may belong
to two or more categories.

2) I agree that defining obligation
category and its members is important. Specifying preference and exclusion
among members would also be necessary. Apparently, we need more constraints.
For example, we may need preference on the argument of the obligation.
In the case of "charge" obligation, it is sometimes accompanied
with fee argument, e.g. charge $3. If two obligations of charge $3 and
charge $4 are resulting obligations, some user would need maximum fee ($4),
but some user would need additive fee ($7) as a final resulting decision.


3) I think that one of the important
thing is the scope of the constraint of the obligation. I think how to
combine obligations should be consistent among entire policy specifications
within relevant policies. What do you think?

Best,
Michiharu